Chemical constituents from Saussurea licentiana Hand.-Mazz

Chemical investigation of Saussurea licentiana led to the isolation of ten compounds, and their structures were identified to be dia-aurantiamide acetate (1), (+)-pinoresinol 4-O-β-D-glucoside (2), encelin (3), apigenin (4), luteolin (5), jaceosidin (6), luteolin -7-O-β-D- glucopyranoside (7), α-amyrin (8), β-amyrin (9), taraxasterol (10) on the basis of mass and NMR spectra. This is the first report on the occurrence of compounds 1, and 2 in the genus Saussurea while 1 is reported for the first time from Asteraceae. This work also represents the first phytochemical work on the whole plants of S. licentiana.     

Calculation of substrate binding affinities for a bacterial GH78 rhamnosidase through molecular dynamics simulations

Ram2 from Pediococcus acidilactici is a rhamnosidase from the glycoside hydrolase family 78. It shows remarkable selectivity for rutinose rather than para-nitrophenyl-alpha-l-rhamnopyranoside (p-NPR). Molecular dynamics simulations were performed using a homology model of this enzyme, in complex with both substrates. Free energy calculations lead to predicted binding affinities of −34.4 and −30.6 kJ mol⁻¹ respectively, agreeing well with an experimentally estimated relative free energy of 5.4 kJ mol⁻¹. Further, the most relevant binding poses could be determined. While p-NPR preferably orients its rhamnose moiety toward the active site, rutinose interacts most strongly with its glucose moiety. A detailed hydrogen bond analysis confirms previously implicated residues in the active site (Asp217, Asp222, Trp226, Asp229 and Glu488) and quantifies the importance of individual residues for the binding. The most important amino acids are Asp229 and Phe339 which are involved in many interactions during the simulations. While Phe339 was observed in more simulations, Asp229 was involved in more persistent interactions (forming an average of at least 2 hydrogen bonds during the simulation). These analyses directly suggest mutations that could be used in a further experimental characterization of the enzyme. This study shows once more the strength of computer simulations to rationalize and guide experiments at an atomic level.     

QTL identification of grain protein concentration and its genetic correlation with starch concentration and grain weight using two populations in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

Protein is one of the three main storage chemical components in maize grains, and is negatively correlated with starch concentration (SC). Our objective was to analyse the influence of genetic backgrounds on QTL detection for protein concentration (PC) and to reveal the molecular genetic associations between PC and both SC and grain weight (GWP). Two hundred and eighty-four (Pop1) and 265 (Pop2) F_2:3 families were developed from two crosses between one high-oil maize inbred GY220 and two normal maize inbreds 8984 and 8622 respectively, and were genotyped with 185 and 173 pairs of SSR markers. PC, SC and GWP were evaluated under two environments. Composite interval mapping (CIM) and multiple interval mapping (MIM) methods were used to detect single-trait QTL for PC, and multiple-trait QTL for PC with both SC and GWP. No common QTL were shared between the two populations for their four and one PC QTL. Common QTL with opposite signs of effects for PC and SC/GWP were detected on three marker intervals at bins 6.07–6.08, 8.03 and 8.03–8.04. Multiple-traits QTL mapping showed that tightly-linked QTL, pleiotropic QTL and QTL having effects with opposite directions for PC and SC/GWP were all observed in Pop1, while all QTL reflected opposite effects in Pop2.     

The effect of family structure on the likelihood for kin-biased distribution: an empirical study of brown trout populations

This study is aimed at evaluating the likelihood that kin-biased distribution will be expressed or detected in a range of brown trout ( Salmo trutta ) populations as a function of family size. Microsatellite analysis indicated that fewer full- and half-siblings were found in populations with larger effective population sizes, while more full- and half-siblings were found in populations with lower effective population size. It is suggested that kin-biased distribution and hence kin-biased behaviours are not likely to be expressed equally frequently in all populations since the number of close relatives will vary among populations and, hence, the opportunity for relatives to interact differs among populations. These findings can, at least partly, explain the discrepancy among previous studies of kin-biased distribution in wild salmonids under natural conditions. Effective population size could, hence, be used to predict the salmonid populations in which kin-biased distribution are more likely to occur and be detected.     

Proacaciberin,A cyanogenic glycoside from Acacia sieberiana var. Woodii

A new cyanogenic glycoside isolated from pods of Acacia sieberiana var. woodii has been shown by chemical and spectroscopic methods to be (2S)-2-[(6-O-α-l-arabinopyranosyl-β-d-glucopyranosyl)oxy]-3-methylbut-3-enenitrileo. Acid-catalysed hydrolysis of the glycoside afforded arabinose and proacacipetalin, and base-catalysed double-bond migration gave 2- [(6-O-α-l-arabinopyranosyl-β- d-glucopyranosyl)oxy ]-3-methylbut-2-enenitrile.     

Identification of chalcone synthase genes and their expression patterns reveal pollen abortion in cotton

Chalcone synthase (CHS) is a key enzyme and producing flavonoid derivatives as well play a vital roles in sustaining plant growth and development. However, the systematic and comprehensive analysis of CHS genes in island cotton (G. barbadense) has not been reported yet especially response to cytoplasmic male sterility (CMS). To fill this knowledge gap, a genome-wide investigation of CHS genes were studied in island cotton. A total of 20 GbCHS genes were identified and grouped into five GbCHSs. The gene structure analysis revealed that most of GbCHS genes consisted of two exons and one intron, and 20 motifs were identified. Twenty five pairs duplicated events (12 GbCHS genes) were identified including 23 segmental duplication pairs and two tandem duplication events, representing that GbCHS gene family amplification mainly owned to segmental duplication events and evolving slowly. Gene expression analysis exhibited that the GbCHS family genes presented a diversity expression patterns in various organs of cotton. Coupled with functional predictions and gene expression, the abnormal expression of GbCHS06, 10, 16 and 19 might be associated with pollen abortion of CMS line in island cotton. Conclusively, GbCHS genes exhibited diversity and conservation in many aspects, which will help to better understand functional studies and a reference for CHS research in island cotton and other plants.     

Preparation and evaluation of soluble epoxide hydrolase inhibitors with improved physical properties and potencies for treating diabetic neuropathic pain

Soluble epoxide hydrolase (sEH), a novel therapeutic target for neuropathic pain, is a largely cytosolic enzyme that degrades epoxy-fatty acids (EpFAs), an important class of lipid signaling molecules. Many inhibitors of sEH have been reported, and to date, the 1,3-disubstituted urea has the highest affinity reported for the sEH among the central pharmacophores evaluated. An earlier somewhat water soluble sEH inhibitor taken to the clinic for blood pressure control had mediocre potency (both affinity and kinetics) and a short in vivo half-life. We undertook a study to overcome these difficulties, but the sEH inhibitors carrying a 1,3-disubstituted urea often suffer poor physical properties that hinder their formulation. In this report, we described new strategies to improve the physical properties of sEH inhibitors with a 1,3-disubstituted urea while maintaining their potency and drug-target residence time (a complementary in vitro parameter) against sEH. To our surprise, we identified two structural modifications that substantially improve the potency and physical properties of sEH inhibitors carrying a 1,3-disubstituted urea pharmacophore. Such improvements will greatly facilitate the movement of sEH inhibitors to the clinic.